1. Field of the Invention
The present invention relates to an organic electro-luminescent device provided with electric light emitting elements used for displays, and display light sources, and the like, a manufacturing method for the same, and electronic equipment.
2. Description of the Related Art
The development of light emitting elements using organic materials for spontaneous light emitting-type displays in place of liquid crystal displays has recently been proceeding at a rapid pace. With respect to an organic electro-luminescent device equipped with a light emitting component using an organic material in the light emitting layer, a related art method for forming a low molecular weight layer using an evaporation process is disclosed from page 913 in Appl. Phys. Lett. 51 (12), 21 Sep. 1987, and a related art method for coating a large molecular weight layer is disclosed from page 34 of Appl. Phys. Lett. 71 (1), July 1997.
In the case of using a low molecular weight material for coloring, a light emitting material differing from that of mask lifting is vapor deposited and formed onto the desired image. On the other hand, in the case of a large molecular weight material, much attention is being placed on performing the coloring using an ink jet method, due to refinement and ease with which the patterning can be accomplished. The following examples are related art methods for forming an organic electro-luminescent component by such an ink jet method: Japanese Patent Application, First Publication No. Hei 7-235378, Japanese Patent Application, First Publication No. Hei 10-12377, Japanese Patent Application, First Publication No. Hei 10-153967, Japanese Patent Application, First Publication No. Hei 11-40358, Japanese Patent Application, First Publication No. Hei 11-54270, and Japanese Patent Application, First Publication No. Hei 11-339957.
In addition, from the standpoint of component manufacturing, in order to enhance the light emitting efficiency and durability, the formation of a hole injection/transport layer between the electrode and light emitting layer is widely performed as disclosed from page 913 in Appl. Phys. Lett. 51 (12), 21 Sep. 1987. Formation of a layer has been performed by a coating process, such as spin coating or the like, using a conductive macromolecule as the buffer layer and/or hole injection/transport layer, e.g., a polythiophene derivative and/or polyaniline derivative (Nature, 357, 477, 1992). With respect to a low molecular weight material, formation of a layer using a phenylamine derivative, as the hole injection/transport layer, by evaporation has been reported.
The aforementioned ink jet methods are extremely effective for simply forming a layer having a refined pattern without wasting the light emitting layer material including the organic electro-luminescent material.
When forming a light emitting layer using an organic electro-luminescent material according to an ink jet method, a composition is employed which includes a solute and solvent, wherein the aforementioned solute includes an organic electro-luminescent material.
As the aforementioned composition, it is possible to use a composition including only one type of organic electro-luminescent material. However, compositions including a plurality of organic electro-luminescent materials are more widely used. For example, by mixing a light emitting material and a fluorescent material, it is possible to change the light illuminated from the aforementioned light emitting material to a light having a different wavelength due to the presence of the aforementioned fluorescent material.
In this manner, in the case of a plurality of organic electro-luminescent materials, in order to obtain the desired light characteristics, it is necessary to form a layer in a state in which each of the aforementioned organic electro-luminescent materials is uniformly mixed without separation therefrom.
However, the droplets used in the formation of a thin layer according to the ink jet method are extremely small, and the evaporation time is short. As a result, the solvent molecules that are evaporated from the droplets are saturated prior to being sufficiently dispersed from the substrate area, such that even the resultant thin layer is re-dissolved. Furthermore, at the time of re-dissolving the aforementioned, the respective organic electro-luminescent materials phase separate from each other, which in turn results in problems, such as degradation of the performance characteristics of the organic electro-luminescent device.